auto determine nullable or not from json value optional null values

consider a case like JSON below
`{"a": [
      {
        "b": "",
        "c": "",
        "d": ""
      },
      {
        "a": ""
      }
    ]
  }`
then b & c should be nullable values but b & c are created as not nullable types.
auto determine nullable or not from JSON value can't recognize this.